New AP Defensive item

With all the presson changes I wanted to make an item that can help immobile mages with the amount to AD and damage reduction that's going to be add to the game. I haven't come up with a name for it yet.

[Untitled] Cost 2800 80 AP 45 Armor Builds out of : +

Unique Passive - Generates Momentum stacks while moving, up to 100, granting up to +60 bonus movement speed. You lose all stacks of momentum upon taking damage and can't gain any more for secs. (You start gain stacks 3 secs after not taking damage).

Unique active - At 100 stacks you can active this item to receive 60 MS that decays over 3 secs.

Notes on the item.

I build this item to be a proactive choice to being dived on my bruisers and assassins the item doesn't do much once you you get caught. will still be strong because it will give you more AP , armor and it can save your live if you get hit. I was going to have it build out of + and give the mana front passive as well but i realized that would be too strong. Let me know what you guys. And a red post about it would be great.